【原创】OPENGL加载BMP纹理图的方式

方法一：

首先获取位图句柄

HBITMAP hBmp = (HBITMAP) ::LoadImage (AfxGetResourceHandle(),MAKEINTRESOURCE(IDB_BITMAP1), IMAGE_BITMAP, 0, 0,LR_CREATEDIBSECTION);

然后根据位图句柄得到位图信息

BITMAP BM;

::GetObject (hBmp, sizeof (BM), &BM);

最后根据位图信息中的RGB值建立纹理

gluBuild2DMipmaps( GL_TEXTURE_2D, 3, BM.bmWidth, BM.bmHeight,GL_BGR_EXT, GL_UNSIGNED_BYTE,BM.bmBits);

方法二：

首先用OpenGL辅助库获得位图信息

 AUX_RGBImageRec* TextureImage[1];

 TextureImage[0]=auxDIBImageLoad("1.bmp");

然后建立纹理

 gluBuild2DMipmaps(GL_TEXTURE_2D, 3, TextureImage[0]->sizeX, TextureImage[0]->sizeY, GL_RGB, GL_UNSIGNED_BYTE, TextureImage[0]->data);

方法三：

从底层做，需要了解bmp文件的结构，首先读取bmp文件结构，包括文件头、信息头和数据，数据用于后面定义纹理

 1 long ImageWidth=256;
 2 long ImageHeight=256; 
 3 GLubyte Image[256][256][3];
 4 void ReadHeader(FILE *fp , BITMAPFH * p_bitmapheader , BITMAPIH *p_bitmapinfo) 
 5 {
 6  fseek(fp, 0, SEEK_SET) ;
 7  fread( &p_bitmapheader->bfType,sizeof(unsigned short), 1, fp );
 8  fseek(fp, 2, SEEK_SET) ;
 9  fread( &p_bitmapheader->bfSize,sizeof(unsigned long), 1, fp );
10  fseek(fp, 6, SEEK_SET) ;
11  fread( &p_bitmapheader->bfReserved1,sizeof(unsigned short), 1, fp );
12  fseek(fp, 8, SEEK_SET) ;
13  fread( &p_bitmapheader->bfReserved2,sizeof(unsigned short), 1, fp );
14  fseek(fp, 10, SEEK_SET) ;
15  fread( &p_bitmapheader->bfOffBits,sizeof(unsigned long), 1, fp );
16  fseek(fp, 14, SEEK_SET) ;
17  fread( &p_bitmapinfo->biSize, sizeof(unsigned long), 1, fp );
18  fseek(fp, 18, SEEK_SET) ;
19  fread( &p_bitmapinfo->biWidth, sizeof(unsigned long), 1, fp );
20  
21  fseek(fp, 22, SEEK_SET) ;
22  fread( &p_bitmapinfo->biHeight, sizeof(unsigned long), 1, fp );
23  
24  fseek(fp, 26, SEEK_SET) ;
25  fread( &p_bitmapinfo->biPlanes, sizeof(unsigned short), 1, fp );
26  
27  fseek(fp, 28, SEEK_SET) ;
28  fread( &p_bitmapinfo->biBitCount, sizeof(unsigned short), 1, fp );
29  
30  fseek(fp, 30, SEEK_SET) ;
31  fread( &p_bitmapinfo->biCompression, sizeof(unsigned long), 1, fp );
32  
33  fseek(fp, 34, SEEK_SET) ;
34  fread( &p_bitmapinfo->biSizeImage, sizeof(unsigned long), 1, fp );
35  
36  fseek(fp, 38, SEEK_SET) ;
37  fread( &p_bitmapinfo->biXPelsPerMeter, sizeof(unsigned long), 1, fp );
38  
39  fseek(fp, 42, SEEK_SET) ;
40  fread( &p_bitmapinfo->biYPelsPerMeter, sizeof(unsigned long), 1, fp );
41  
42  fseek(fp, 46, SEEK_SET) ;
43  fread( &p_bitmapinfo->biClrUsed, sizeof(unsigned long), 1, fp );
44  fseek(fp, 50, SEEK_SET) ;
45  fread( &p_bitmapinfo->biClrImportant, sizeof(unsigned long), 1, fp );
46  
47 }
48 void ReadBitmapFile()
49 {
50  BITMAPFH bitmapheader ;
51  BITMAPIH bitmapinfo ;
52  FILE *fp;
53  
54  fp = fopen("6.bmp" , "r") ;
55  if(!fp)
56  {
57    puts("Read file failed.") ;
58    return;
59  }
60  
61  ReadHeader(fp, &bitmapheader , &bitmapinfo) ;
62  
63  if(bitmapinfo.biBitCount != 24)
64  {
65    puts("UNSUPPORT") ;
66    return;
67  }
68  ImageWidth = bitmapinfo.biWidth;
69  ImageHeight = bitmapinfo.biHeight;
70 
71  int i=bitmapheader.bfOffBits;
72  while(i<bitmapheader.bfSize)
73  {
74    for(int j=0;j<ImageWidth;j++)
75     for(int k=0;k<ImageHeight;k++)
76     {
77      fseek(fp, i, SEEK_SET) ;
78      fread(Image[j][k]+2, 1, 1, fp) ;
79      fseek(fp, i+1, SEEK_SET) ;
80      fread(Image[j][k]+1, 1, 1, fp) ;
81      fseek(fp, i+2, SEEK_SET) ;
82      fread(Image[j][k], 1, 1, fp) ;
83     
84      i=i+3;
85     }  
86  } 
87  
88  fclose(fp) ;
89 }
90 glTexImage2D(GL_TEXTURE_2D,0,3,ImageWidth,ImageHeight,0,GL_RGB,GL_UNSIGNED_BYTE,&Image[0][0][0]);

 

#include <gl\glext.h>

这是因为后面的GL_BGR_EXT是定义在这个头文件里的，因为BMP格式是按Blue,Green,Red顺序储存图像数据的，这与OpenGL中正好相反。GL_BGR_EXT就是完成两者之间的转换的。

下面就是不用AUX库来加载BMP图片作为纹理的函数：

 1 bool LoadTexture(LPTSTR szFileName, GLuint &texid)      // Creates Texture From A Bitmap File
 2 {
 3 HBITMAP hBMP;              // Handle Of The Bitmap
 4 BITMAP BMP;              // Bitmap Structure
 5 
 6 glGenTextures(1, &texid);           // Create The Texture
 7 hBMP=(HBITMAP)LoadImage(GetModuleHandle(NULL), szFileName, IMAGE_BITMAP, 0, 0, LR_CREATEDIBSECTION | LR_LOADFROMFILE );
 8 
 9 if (!hBMP)               // Does The Bitmap Exist?
10    return FALSE;             // If Not Return False
11 
12 GetObject(hBMP, sizeof(BMP), &BMP);         // Get The Object
13                   // hBMP:        Handle To Graphics Object
14                   // sizeof(BMP): Size Of Buffer For Object Information
15                   // &BMP:        Buffer For Object Information
16 
17 glPixelStorei(GL_UNPACK_ALIGNMENT, 4);        // Pixel Storage Mode (Word Alignment / 4 Bytes)
18 
19 // Typical Texture Generation Using Data From The Bitmap
20 glBindTexture(GL_TEXTURE_2D, texid);         // Bind To The Texture ID
21 glTexParameteri(GL_TEXTURE_2D, GL_TEXTURE_MIN_FILTER, GL_LINEAR); // Linear Min Filter
22 glTexParameteri(GL_TEXTURE_2D, GL_TEXTURE_MAG_FILTER, GL_LINEAR); // Linear Mag Filter
23 glTexImage2D(GL_TEXTURE_2D, 0, 3, BMP.bmWidth, BMP.bmHeight, 0, GL_BGR_EXT, GL_UNSIGNED_BYTE, BMP.bmBits);
24 
25 DeleteObject(hBMP);             // Delete The Object
26 
27 return TRUE;              // Loading Was Successful
28 }